CHARLOTTE, N.C. -- Two days after an elementary school shooting in South Carolina, NBC Charlotte is showing you some new technology created by a Charlotte-Mecklenburg Police officer that could help to prevent mass shootings in schools and office buildings in the future.

The Barricade Box is just hitting the market and Sergeant Chris Kopp says it's already in 18 local schools.

"Right now (locally) it's just in the Charlotte area," Kopp said. "There are a lot of schools still testing the device."

It's also in the office of the company he owns, Lockdown International.

"We're seeing more and more of these happening on a daily basis whether it's at a school or just in an office building," Kopp said.

The box has a cap that you pop off, before stretching a cord around a door handle and hooking it back on the box. It's a strategy to keep the door secure, and even an elementary school student can do it in seconds.

"Trying to find that key, put the little key in the keyhole, and lock it while somebody's shooting at you, is extremely stressful," Kopp said.

One of these can be installed in under 10 minutes, and each one costs around $50. With around 80 classroom doors in a school, it would cost a school around $4000 to be fully secure. Kopp says keeping people safe is well worth it.

"A lot of people get very active when a situation happens and then the interest gets lost," Kopp said. "They think 'It's not going to happen here,' or people don't remember."